Please read my last post, as I have found that this is NOT nessasary to do. Sorry ...


Being that I have just about completely disassembled my Mini bolt by bolt, I have learned a few things along the way. Always learning....

To everyone who has lowered you Mini or plans to, there is something that you need to also do. Some may know, but I have never seen it mentioned here.
After lowering most people do take there cars to get aligned. Ask your alignment guy to please loosen the rear trailing arm bushing bolt and then tighten it back up when the it's up on the lift (when the suspension is fully loaded). This will neutralize any preload that is on that rear trailing arm bushing from lowering the car. Otherwise the car will be preloaded and may have increased and unwanted rebound. this is especially important to lightened Minis. Also if you are on coilovers and are planning to corner balance it, this bushing must be neutralized first.

The front control arm bushing will also be preloaded, but at this time I have not looked into how it can be neutralized. I don't think it can, but one, it's not as firm as the rear, and two, the front being heavier will not be as effected by it.

Greg V

 

How necessary is this? I lowered my MINI and didn't do it. What are the side effects if I dont?

 

Time for my wild-***-guessing...

Greg said "Otherwise the car will be preloaded and may have increased and unwanted rebound". Here's my interpretation of that:

If you don't un-pre-load that part of the suspension, it will basically always be trying to compress the spring of the rear suspension. You hit a bump, the spring compresses (with that little extra compression from the pre-load)... then comes the "rebound" phase where the spring extends back to normal length. With the extra compression (from the pre-load) comes extra force in the rebound phase.

Nothing too horrible will happen from all this, but the back of the car will be a little "bouncier" than it should be. And it probably won't help your damper's life expectancy (especially if they're the already overtaxed stock dampers with lowering springs).

Of course, I'm not a suspension expert (yet). I'll have no problem editing / deleting this post when someone who knows more than me tells me I've got it all wrong.

 

Snid, I think you've hit it right on the head... I'm no expert either, but it makes sense with my little suspension knowledge!

 

This all sounds reasonable, but I just spent 2 hours of an alignment shop's time to get my car done, and *now* I hear I have to do this. Will it affect my alignment, or can I simply jack my car up, and loosen this bolt and then tighten it again? (Ah, I hope the answer is yes...)

cheers,

 

This does not "have" to be done. It's just something that you would want to do if you are looking to set your car up properly in order to gain the best performance. I might bet that at most 1% of the people who have lowered their car have done this, if any at all. So you are in lots of company if you decide not to.
If you do it, then you can only do it while the suspension is loaded, meaning that the car must be off any jacks and the full weight is on all four wheels. That's why an alignment lift is the perfect place to do it.
This is the way the car is set up at the factory. Unfortunately this detail has gotten lost as part of the lowering procedure.

 

i didn't really 'decide' not to, but just haven't done it.... and probably won't.

 

Yeh, but Ken, you've been running HSports without adjustable control arms and camber plates for nearly a year (of posts at least) and proclaiming it's "all good". I believed you for quite some time after I did the same, but now that I have adjustment in my suspension, I find my car to be undeniably superior to the "stock HSport with no other mods" setup. You really should consider doing it yourself...
I'm now (thanks to PM advice from onasled (Greg V)) totally a "brakes and suspension" guy--I'd actually trade all my other mods for these two!

cheers,

 

Great info Onasled. I never thought to check the rear bushing.

I included info about distorting bushings during the reinstallation process...probably a year or so ago...my observations were not taken too seriously. In fact, as Onasled and snid point out, many shop manuals explicitly point out a procedure that requires final torquing AFTER the full weight of the car is on all four wheels - including final ride height to specifically prevent bushing preload. It may not be noticeable to some, but it will show up when your car is corner balanced.

Those with the Powerflex front bushing need not worry. you have to see to understand.

 

oh look, a challenger! hehehe. lol

mine's for street and it's good. you never see me posting about
track setup or autox. you ever wonder why? cause i don't use
my car other than for street.

so, misterman hotshot guru, what toe and camber angles do you
propose for street running 16x7.5 205/50/16 42mm offset?
im just kidding.

my theory to a car is, why change something that you don't
really need improvement on? the H-sport+22mm swaybar setup
is fine. don't need camber rods or toe rods or any thing else.
(although my stock dampers are starting to loosen up so will
get some aftermarkets soon to replace). i will know if i did.

a lot times people change something on their car and it's all
in their head. then later find more problems associated with it
and end up going back to the simple times.
(im not implying about onasled who's been racing his rocket).

 

Another reason to run aftermarket rear arms is to reduce the geometry changes (static and dynamic) caused by the soft/worn bushings. I recently found that my rear camber went from -1.5* to -2.5* without any ride height changes. Hard chargers with 50k+ miles know how out of control these cars can get with worn bushings. I saw a post where a couple ended up trading in thier mini because of how bad the car handled.

 

not sure why you chose to quote my post, but that's very interesting
on your car.

 

I applied torque to the rear trailing arm bolts while under load today and had a couple of discoveries. On the passenger side the bolt was extremely tight more like 200 ft-lb instead of 125 and on the driver’s side the bolt was only snug; there’s no way they used proper torque at the factory. Also each bushing had minor cracks on the bolt side; more on the over tightened side. I’ll have to replace the entire bracket since stock bushings alone are not available. At least they’re only $84 list which isn’t too bad.

After observing the trailing arm articulation and movement on the bolt side, I think the end of the arm does very little twisting. The majority of motion is only up and down (11 o’clock to 5 o’clock) so in actuality the end piece just rocks unlike the pivoting front control arm. I doubt that any pre-load would be in effect after lowering from the stock ride height. I took ground to brake rotor measurements before and after and there was no difference in the static state. When the vehicle is in motion loads will be much greater so the suspension shouldn’t see any resistance if pre-load wasn’t enough to elevate the trailing arm after applying torque at compression. Of course those of you engaged in competition should cover all the bases.

 

Just to clarify, .... it seems this thread has drifted to control arms rather then what was originally posted, which was trailing arms.

 

I corrected my nomenclature, one of my common mistakes, sorry.

My observations were of a pre November 2004 build trailing arm and bracket (my 12/02). It may very well be later builds have a different orientation of the bracket in relation to the trailing arm facilitating more pivoting.

It’s easy to see how toe can wander under load with my bushing & bracket design; aftermarket inserts would probably control the in/out movement, but the augmentation of suspension damping might be less controllable vertically than struts & springs for the dial-in guys.

 

Not an attack, but you state that you don't need anything else than springs and sway bar.

 

...and my camber has not increased like yours over the years.
i don't still don't know why you're quoted my post...

 

Don't worry about it. I must have read something out of context.

 

Greg, information like this is what makes NAM such a neat community. This is very timely for me, as my new tires go on tomorrow, and I'm off to the alignment shop immediately thereafter.

 

np.

 

Below is how I observed the articulation of the trailing arm and put it in a position to re-torque the end bolt. Here’s a link to another thread with a picture of the early model bushing close up on the bolt side (post #18) https://www.northamericanmotoring.co...ad.php?t=68901. There is a rectangular metal insert that bolts to the trailing arm within the bushing; it only goes one way so there’s no opportunity for “loading”, also, it doesn’t allow for twisting action.

 

Not sure I follow Keith???

 

k-huevo: I'm having difficulty interpreting your post. Do you mean that certain model rear trailing arm bushings don't require the "de-loading" that onasled refers to in post #1 above?
And is your photo intended to show the suspension as it sits fully loaded when the wheel is on the car and supporting the weight of the car? Is this a method for accessing the trailing arm bolts without the car being on an alignment lift?

cheers,

 

meb, with the pre-March 03 (for sure this time) bracket and bushing the weak point would be a load pulling out or pushing (scrubbing speed, rotating) towards the bushing. Movement in these directions would turn the wheel left or right affecting toe; albeit a small amount. There is a bracket/plate under the bolt (which hangs out in space without the insert) to hold the outer insert (limiting travel in that direction) and the insert on the arm side held in by the arm. The sandwich effect would keep the bushing from moving like a diaphragm. When the arm is going up or down the trailing arm would come against it like a bump stop limiting travel. I’m assuming the lack of compressibility would be a constant that couldn’t be dialed out if need be. I’m still going to give it a try and it won’t be hard to reverse. gandini, the early model seems to be non-loadable or un-loadable for “de-loading” .

The later model bushing, bracket and trailing arm is different (so is the cross member support and almost every other rear part). The bushing sticks out at both ends of the bracket and cups the conical end of the trailing arm (the earlier arm is flat on the end and mates to the rectangular metal insert integrated within the bushing) and cups the dished support (flat bracket for the early model) under the bolt. Until I get to play with one I can only speculate how the latest model performs.

gandini, the jack & stands method is one way to compress the suspension and give you enough room to maneuver with tools. The wheel was removed because I wanted a good look at the arm action and the drop link needed to be disconnected. If you had two jacks you could put one under each wheel and do the same thing without having to remove the tires. With my breaker bar and socket the arm had to be raised in full compression in order to lower the bolt to an angle I could get a good purchase on. A torque wrench would have to have a flexible head to get in there too. Also in my case I removed the rivets and screw for the rubber guard so it could be moved out of the way and poked the clips (two white ones) through for the trim to provide a little more room. With the wheels removed it took me about three hours on the passengers side because of the learning curve, jacking it up & down watching reference points, and removing the stubborn bolt; the driver’s side took about twenty minutes.

And I thought a picture would tell the story.

 

Onasled and Keith, I just got my M7 sprung/H&R rear lower control armed '05 aligned by the most impressive alignment guy I've ever met (not that I've met that many, but this guy has the local Ferrari business, along with Aston Martin, BMW, etc. He's good.). Anyway, I printed Onasled's original post, and gave it to him; he read it and said "He's right! I'll check it."

When I got the car back, he said that the left was more bound than the right, but that both needed some 'release'. So FWIW, it appears the later models can potentially benefit from this advice. Thank you Onasled for sharing this with the community.